1. Field of the Invention
This invention relates to photometric chemical analyzers. More particularly, this invention relates to an improved photometric analyzer capable of performing kinetic rate measurements of enzyme activity, end-point determinations of metabolites, and fixed-time substrate analyses.
2. Description of the Prior Art
The measurement of absorbance of light is an important method of analyzing the chemical composition of fluids. This type of measurement is usually performed by passing a narrow bandwidth spectrum of visible light through the fluid under test and measuring the amount of light absorbed by the fluid. The degree of absorption is proportional to the concentration of the chemical component or components which will absorb the particular spectrum being applied. By providing the capability of directing spectra of several different wavelengths or colors through the fluid, one may conduct a fairly complete analysis.
The fluid or fluids under consideration are placed in specialized test tubes called cuvettes. The cuvette typically has a square or rectangular cross-section where at least two opposing sides are prefectly or nearly perfectly parallel. The parallel relationship is important for minimizing diffraction of a visible light beam as it passes through the cuvette.
In one known arrangement of a chemical analyzer, several cuvettes are placed together in a line on a platform. A light source is arranged to be passed through each cuvette serially by moving either the light source or the row of cuvettes. A detector is placed on the other side of the cuvettes, in line with the optical path of the light beam emanating from the light source. Finally, a filter which permits only a narrow bandwidth spectrum of visible light to pass is placed in the optical path of the light source between the source and the cuvettes. One cuvette may be left empty to serve as the reference standard.
With the arrangement described immediately above, one is limited to performing a single test on the cuvettes in a batch mode. If one wishes to perform another test on the fluids, a second batch of cuvettes must be assembled.